Some coating compositions are known in the art and are used in a great variety of applications such as for primers, base coats and clear coats in vehicle original coatings and vehicle repair coatings. In this regard, great efforts have been made to develop coating compositions imparting the desired properties to the substrate or article to be coated. For example, coatings have been developed for e.g. protecting against abrasion, chemicals, corrosion, heat or mechanical impact. Furthermore, in vehicle repair coatings, there is an increasing demand in the market for fast drying coating compositions at room temperature.
In this regard, aspartate based coating compositions are well known in the art. For example, EP 0 403 921 describes coating compositions with binders based on a polyisocyanate component and an isocyanate-reactive component containing specific secondary polyamines. These secondary polyamines are also called polyaspartic acid derivatives and are based on reaction products of primary polyamines and diesters of maleic and/or fumaric acid. EP 0 470 461 also describes coating compositions for vehicle refinish applications containing a polyisocyanate component and an isocyanate-reactive sterically hindered diamine prepared from 3,3′-dimethyl 4,4′-diamino dicyclohexylmethane and maleic diethylester. The isocyanate-reactive component further contains a hydroxyl-functional poly(meth)acrylate or mixtures of hydroxyl functional poly(meth)acrylates and polyesterpolyols. WO 2005/073188 refers to aspartates which are prepared by first reacting a di- or polyamine with an unsaturated ester and then reacting the resultant product with a maleimide. U.S. Pat. No. 5,633,336 A refers to low-viscosity (cyclo)-aliphatic polyamines containing urea groups and having more than two amino groups that may be prepared by reacting (cyclo)aliphatic diamines with polyisocyanates containing isocyanurate groups or biuret groups. Such polyamines are useful as components in PUR reaction finishes and coating and adhesive compositions. WO 2013/098186 A1 refers to an aqueous urethane resin composition consisting mainly of the following (A) component and containing the following (B) and (C) components: (A) hydrophilic polyol, (B) water dispersible polyisocyanate, (C) aspartic acid ester having a secondary amino group. WO 2009/086026 discloses a transparent organic solvent-based clear coat coating composition including at least one binder with functional groups containing active hydrogen, in particular hydroxyl groups, at least one polyisocyanate cross-linking agent with free isocyanate groups and at least one epoxy-functional silane. US 2009/0226645 A1 refers to coating composition including as component I, a) a polyaspartic acid ester including the reaction product of one more diamines, one or more difunctional acrylate-containing compounds and one or more maleic/fumaric acid esters; b) at least one moisture scavenger; c) at least one deaerator; d) at least one plasticizer; and e) optionally additives; and as component II, one or more polyisocyanates. US2007/160851 A1 refers to coating compositions including a polyurea formed from a reaction mixture including isocyanate and a (meth)acrylated amine, wherein the (meth)acrylated amine is the reaction product of a polyamine and a (meth)acrylate; when the (meth)acrylate includes a poly(meth)acrylate, the reaction product further includes a mono(meth)acrylate and/or a monoamine.
The above coating compositions possess fast curing times. However, if a di- or polyamine is reacted with a fumarate diester, the reaction times are very slow which causes strong discoloration in the obtained reaction product and coating compositions prepared therefrom. Moreover, unreacted fumarate diester causes further disadvantages as it remains as a non-reactive component in the final formulation. The disadvantages are reflected by an overall worsening in the balance of potlife and drying performance versus substrate and/or intercoat adhesion. The same discoloration and disadvantages of the reaction products and coating compositions prepared therefrom are obtained in case a maleate diester is reacted with a di- or polyamine as the reaction typically goes partially through fumarate diester isomerisation. Thus, the balance of potlife of these coating compositions and properties such as substrate adhesion and/or intercoat adhesion after application/drying as well as color and/or color stability of the liquid paint are not sufficient for certain applications.
Thus, the object of the present disclosure is to provide a coating composition having a well-balanced drying performance, i.e. fast curing times at a sufficient potlife, in some embodiments a potlife of at least 30 min at room temperature, mechanical properties such as substrate adhesion and intercoat adhesion in a multi-layer structure, abrasion, chemical and corrosion resistance, and optical properties, such as a low initial color and good color stability of the liquid paint.